Regardless of what version, simply fill with a standard line pattern and rotate the pattern within the object. You can either use the "~" key to affect only the fill while using any of the modifier tools (rotate, scale, shear or reflect) or Option-Click with one of the tools, type in an angle, etc., and uncheck "Object". Once you have the angle needed, save it as a style and reuse on any object. If you want to maintain stroke attributes when assigning the fill style, build the style without a stroke attribute then hold "Option" when assigning the style. AI will layer the new style BELOW any current object appearances.
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